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Tannoy HPD 385

I’ve been a fan of big diameter co-axial or full range drivers for quite some time. Tannoy HPD 385 is the main actor in this chapter but in the course of 10 years, I’ve tested quite a 12” and above coaxial drivers, like the Soundcraftsmen 2640TX, Altec Lansing Super Duplex 604D, Tannoy DCC 3939 (Arundels), Tannoy DCC3149, and lastly the Tannoy HDP 385.

I do not know why but I’ve not been very lucky in dealing with buying audio equipment. The Tannoy HPD 385 that I got had some issues. One side of the tweeter is producing some scratchy sound. I did not really noticed until D-man came over and pointed it out to me as I thought it was from the music source.

I’ve tried several methods on cleaning the voice coil gap of debris and dusts, realigning the tweeter, changing the bass driver mounting positions in the cabinet, changing the tweeter mounting orientation and etc but all in vain. The scratchy sound persisted! Contacting the seller did not help as he turned defensive after a few emails, as if I’m a troublemaker or so.

Anyhow, I ordered an original Tannoy replacement tweeter from The Speaker Exchange (reconingspeakers.com) and it solved the problem. Cathy from The Speaker Exchange was a nice person to deal with. I reconed my Tannoy DCC 3149 with Cathy previously. I was in for a treat as the new tweeter is made with modern materials and it sounded much better compared to the originals.

I hope to get another tweeter to replace the other OK tweeter for the other side of the speakers since right now the high frequency is out of balance. The new tweeter is more extended and airy compared to the original tweeter that is warmer and have more “tone”. I suspect the efficiency is higher as well for the new tweeter. I actually liked the new tweeter more now.

On the other hand, for some that likes the modern Tannoy Prestige series, perhaps a conversion the foam surround generally found on Tannoy HPD 385 to hard edge cloth surround used in the modern Tannoy Prestige series speakers would be nice.

In addition to the benefits in sound, that would remove the needs to change the surrounds or recone it in every 10-15 years as the Tannoy HPD 385 foam surround tends to rot since it is made of foam. The new material is from rubberized double roll cloth surround that is supposed to last forever. From the various feedbacks of owners who did it, it looks like a favorable sonic upgrade too! This would be up next if I’ve the time and money to do so!

Enough with the background and ramblings, let’s get back to the topic on DIY Tannoy HPD 385 speakers.

Above are the actual Tannoy HDP 385 drivers that I purchased as used units. Cosmetic wise they’re in very good conditions. According to the seller, they have been refoamed few years ago and it should last for at least another 7-10 years (hopefully!). The recone job was not fantastic but was acceptable as getting the new surround and have it done locally would be a pain.

For Tannoy HPD 385, there are quite a number of cabinet designs to choose from. Refer below for the cabinet drawings, and the attached PDF file on the description of the driver + cabinet specifications. Some even tried it with the Tannoy GFR (Guy R. Fountain) cabinet. If you’re bold and have access to a good carpenter, or a master carpenter yourself, you can try the Autograph cabinet too.

For me, due to the size and weight constraint, I chose the Tannoy Berkeley design. The other designs would be too big for me to move around and too big for the room. The only sacrifice is on the bass response where Berkeley design would not dive as deep as the other bigger brothers. I did some modifications to the Berkeley design to make it a huge stand mount instead of a small floor stander. This gives me the flexibility to make the cabinet more rigid, and suitable for placement on stands.

The cabinet is properly braced, and uses marine plywood and solid hardwood from the tropical countries. For the speaker walls, 2 layers of 12mm plywood are used and the final external layer uses 12mm hard wood as finishing. General bracing uses 1” x 2” timber and 1” thick timber is used for front baffle driver mount bracing. You can basically say that it is as solid as rock!

The inner layers are painted with bitumen to damp the cabinet further. You can see the cross bracing in the picture above too.

This is the inner layer outlook using plywood before another layer of 12mm hardwood is mounted on top of it.

This is the sound diffuser panel mounted at the back of the speaker driver. It helps to make the cabinet more rigid as well.

The lacquer is lighter in color that I expected. Therefore I applied another layer of darker lacquer before applying another few layers of clear coating as finishing. The final finishing is as show in the final picture of my setup.

As I bought the drivers without the crossover, I need to build my own crossover. I considered getting the original crossover from eBay but the price kept me far, far away. If someone would be kind to donate or sell me a pair cheap, that would be nice. Hahaha…

There are 2 other options left for me. Go for active crossover or go with the design from Moxtone Lab. For active crossover path, I thought of going for the Behringer DCX 2496 since it is highly versatile and could be programmed to suit the Tannoy HPD 385 driver. Of course, modifications on the Behringer DCX 2496 is planned if I go this path, to make it sound better. The stock unit needs the modifications to sound good.

Coincidently, the guys from Tannoy Yahoogroup started a design based on the original design from John Ridley. I took the plunge and purchased the crossover kit. I built the crossover and never looked back since. The active crossover worked on 1st power on and it really well. I simply loved it. The only down side is that I’ve to have 2 identical stereo amplifiers to drive the Tannoy HPD 385!

Well, afraid not as the evil Ken used 2 stereo 300B (Carmen) amplifiers to bi-amp the amplifier, making the amplifiers have DIRECT connection to the speaker drivers – being crossover-less! The sound it brings is simply stunning as I could rock the room with just 8 Watts without the crossover sucking away to available power from the amplifier. I wish I’ve the opportunity to compare this with the original passive crossover one day and make some comparisons to share with the readers of DIY Audio Guide.

The end result is simply great. My audio system never sounded so good! The Carmen 300B tube amplifier really matches very well with the Tannoy HPD 385 speaker. The modified Berkeley sits on a custom made ultra solid pair of speaker stands. Bass is good, midrange is warm and thick. The only shortcoming is on the unbalanced highs since the one on the left is with the new tweeter and the one on the right is with the original tweeter.

The other choice that I have in mind is to try 2 x Tripath TA2020-20, or TK2050, or TA2022 class T amplifiers on this speaker. My friend Teoh had tried the TA2024 Sonic Impact (modified of course) on his Tannoy DCC 3839 in a Tannoy GRF cabinet and it sounded really good as well. Bass was much, much deeper than my current setup.